PHP implements scan login

On modern social networks and e-commerce platforms, fast and convenient login methods are one of the important means to attract users. Scanning to log in is one of the simple, fast and secure ways. This article will introduce how to use PHP to implement scan login.

1. Principle of scanning to log in

Scan to log in means that after the user opens the designated App or scans the QR code, the information is sent to the server. The server determines the validity of the information and then returns a credential (token) to complete login verification.

2. Implementation process

1. Preparation work

Before scanning to log in, you need to prepare the following work:

1. PHP application.
2. QR code generation tool.
3. Token generation and verification mechanism.
4. Client (mobile phone or tablet).
5. Generate QR code

You need to use the corresponding library to generate images. This article uses PHP QR Code to generate QR codes.

include "phpqrcode.php";
QRcode::png($data, $filename, $errorCorrectionLevel, $matrixPointSize, 2);

Generating a QR code generally requires passing in a data (data), which can be a link or a string. For example:

$data = "https://example.com/?token=xxxxxx";
QRcode::png($data, "qrcode.png", QR_ECLEVEL_L, 10, 2);

3. Verification token

We need to ensure that the generated token is unique and has a short validity period to ensure security. Consider using jwt (JSON Web Token) to generate tokens. The implementation code is as follows:

// 生成令牌
$secret_key = "your-secret-key";
$header = '{"alg":"HS256","typ":"JWT"}';
$payload = '{"sub":"1234567890","name":"John Doe","iat":1516239022}';
$jwt = base64_encode($header) . "." . base64_encode($payload);
$jwt .= "." . hash_hmac('sha256', $header . '.' . $payload, $secret_key, true);

This is only an implementation description. In actual development, the appropriate encryption algorithm and key need to be selected according to the actual situation.

4. Verify QR code

The steps to verify QR code are as follows:

1. The server generates a uuid for each QR code, Store the uuid in the database and return the uuid to the client;
2. The client obtains the uuid by scanning the QR code;
3. The client sends the uuid to the server;
4. The server queries the database based on the uuid and verifies whether the uuid exists;
5. If the uuid exists and has not expired, a token is generated, stored in the database, and returned to the client;
6. Client Use the token to access content that requires authentication.

The specific implementation of the verification process is as follows:

// php 获取 POST 参数
$uuid = $_POST['uuid'];
// 根据 uuid 查询数据库
if (检查 uuid 是否存在 && 检查 uuid 是否有效) {
    // 生成令牌
    $token = 生成令牌;
    // 保存到数据库
    保存 token 到数据库;
    // 返回给客户端
    echo $token;
}

5. Verification token

After the client obtains the token returned by the server, it can use JWT (JSON Web Token) library parses tokens. The parsed content can contain user information and other relevant verification information. Set the validity period and other security verifications according to the actual situation to ensure that the token will not be used maliciously. An example is as follows:

// 解析 token
$jwt = $_GET['jwt'];
[$header, $payload, $signature] = explode(".", $jwt);
$jwt_hash = hash_hmac('sha256', $header . '.' . $payload, $secret_key, true);
if (base64_decode($signature) == $jwt_hash) {
    // 有效的 token
}

3. Summary

This article introduces the basic process of using PHP to realize scan login: generating QR code, verification token, verification QR code, verification token, This enables the function of scanning to log in. The entire process requires attention to safety and correctness. In actual development, more factors need to be considered, such as the display method of the generated QR code, whether authorization is required, the validity period of the token, etc.

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